base/SOURCES/0753-pid1-include-the-source-unit-in-UnitRef.patch

From c6da3d5d824f7b125b3fd95a961eca98db7febf7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= <zbyszek@in.waw.pl>
Date: Tue, 13 Feb 2018 13:12:43 +0100
Subject: [PATCH] pid1: include the source unit in UnitRef

No functional change.

The source unit manages the reference. It allocates the UnitRef structure and
registers it in the target unit, and then the reference must be destroyed
before the source unit is destroyed. Thus, is should be OK to include the
pointer to the source unit, it should be live as long as the reference exists.

v2:
- rename refs to refs_by_target

(cherry picked from commit 7f7d01ed5804afef220ebdb29f22d8177d0d3a5c)
(cherry picked from commit ff80bfd94181327a5f8e0fbd70b9b7afe0c5545c)

Related: #1729228
---
 src/core/busname.c       |  2 +-
 src/core/dbus-manager.c  |  2 +-
 src/core/dbus-unit.c     |  2 +-
 src/core/load-fragment.c |  6 +++---
 src/core/service.c       |  2 +-
 src/core/slice.c         |  2 +-
 src/core/socket.c        |  4 ++--
 src/core/unit.c          | 35 ++++++++++++++++++-----------------
 src/core/unit.h          | 12 ++++++------
 9 files changed, 34 insertions(+), 33 deletions(-)

diff --git a/src/core/busname.c b/src/core/busname.c
index a5e659049d..97886f1e05 100644
--- a/src/core/busname.c
+++ b/src/core/busname.c
@@ -175,7 +175,7 @@ static int busname_add_extras(BusName *n) {
                         if (r < 0)
                                 return r;
 
-                        unit_ref_set(&n->service, x);
+                        unit_ref_set(&n->service, u, x);
                 }
 
                 r = unit_add_two_dependencies(u, UNIT_BEFORE, UNIT_TRIGGERS, UNIT_DEREF(n->service), true);
diff --git a/src/core/dbus-manager.c b/src/core/dbus-manager.c
index 1766163b33..8267d44e1a 100644
--- a/src/core/dbus-manager.c
+++ b/src/core/dbus-manager.c
@@ -649,7 +649,7 @@ static int transient_unit_from_message(
             u->fragment_path ||
             u->source_path ||
             !strv_isempty(u->dropin_paths) ||
-            u->refs ||
+            u->refs_by_target ||
             set_size(u->dependencies[UNIT_REFERENCED_BY]) > 0)
                 return sd_bus_error_setf(error, BUS_ERROR_UNIT_EXISTS, "Unit %s already exists.", name);
 
diff --git a/src/core/dbus-unit.c b/src/core/dbus-unit.c
index f0f75e01b0..77073308c8 100644
--- a/src/core/dbus-unit.c
+++ b/src/core/dbus-unit.c
@@ -967,7 +967,7 @@ static int bus_unit_set_transient_property(
                                 return -EINVAL;
 
                         if (mode != UNIT_CHECK) {
-                                unit_ref_set(&u->slice, slice);
+                                unit_ref_set(&u->slice, u, slice);
                                 unit_write_drop_in_private_format(u, mode, name, "Slice=%s\n", s);
                         }
                 }
diff --git a/src/core/load-fragment.c b/src/core/load-fragment.c
index f3d0851fe2..1721fea8f3 100644
--- a/src/core/load-fragment.c
+++ b/src/core/load-fragment.c
@@ -1836,7 +1836,7 @@ int config_parse_socket_service(
                 return 0;
         }
 
-        unit_ref_set(&s->service, x);
+        unit_ref_set(&s->service, UNIT(s), x);
 
         return 0;
 }
@@ -2006,7 +2006,7 @@ int config_parse_busname_service(
                 return 0;
         }
 
-        unit_ref_set(&n->service, x);
+        unit_ref_set(&n->service, UNIT(n), x);
 
         return 0;
 }
@@ -2933,7 +2933,7 @@ int config_parse_unit_slice(
                 return 0;
         }
 
-        unit_ref_set(&u->slice, slice);
+        unit_ref_set(&u->slice, u, slice);
         return 0;
 }
 
diff --git a/src/core/service.c b/src/core/service.c
index 69ec916f2d..eaa588863f 100644
--- a/src/core/service.c
+++ b/src/core/service.c
@@ -3299,7 +3299,7 @@ int service_set_socket_fd(Service *s, int fd, Socket *sock, bool selinux_context
         s->socket_fd = fd;
         s->socket_fd_selinux_context_net = selinux_context_net;
 
-        unit_ref_set(&s->accept_socket, UNIT(sock));
+        unit_ref_set(&s->accept_socket, UNIT(s), UNIT(sock));
 
         return unit_add_two_dependencies(UNIT(sock), UNIT_BEFORE, UNIT_TRIGGERS, UNIT(s), false);
 }
diff --git a/src/core/slice.c b/src/core/slice.c
index 1cce3e1217..0985a65286 100644
--- a/src/core/slice.c
+++ b/src/core/slice.c
@@ -76,7 +76,7 @@ static int slice_add_parent_slice(Slice *s) {
         if (r < 0)
                 return r;
 
-        unit_ref_set(&UNIT(s)->slice, parent);
+        unit_ref_set(&UNIT(s)->slice, UNIT(s), parent);
         return 0;
 }
 
diff --git a/src/core/socket.c b/src/core/socket.c
index 3e4cdd467f..8489575de6 100644
--- a/src/core/socket.c
+++ b/src/core/socket.c
@@ -208,7 +208,7 @@ int socket_instantiate_service(Socket *s) {
                 return r;
 
         u->no_gc = true;
-        unit_ref_set(&s->service, u);
+        unit_ref_set(&s->service, UNIT(s), u);
 
         return unit_add_two_dependencies(UNIT(s), UNIT_BEFORE, UNIT_TRIGGERS, u, false);
 }
@@ -313,7 +313,7 @@ static int socket_add_extras(Socket *s) {
                         if (r < 0)
                                 return r;
 
-                        unit_ref_set(&s->service, x);
+                        unit_ref_set(&s->service, u, x);
                 }
 
                 r = unit_add_two_dependencies(u, UNIT_BEFORE, UNIT_TRIGGERS, UNIT_DEREF(s->service), true);
diff --git a/src/core/unit.c b/src/core/unit.c
index 1b8ec9a20e..5376ef862f 100644
--- a/src/core/unit.c
+++ b/src/core/unit.c
@@ -315,7 +315,7 @@ bool unit_may_gc(Unit *u) {
         if (u->no_gc)
                 return false;
 
-        if (u->refs)
+        if (u->refs_by_target)
                 return false;
 
         if (UNIT_VTABLE(u)->may_gc && !UNIT_VTABLE(u)->may_gc(u))
@@ -553,9 +553,8 @@ void unit_free(Unit *u) {
         condition_free_list(u->asserts);
 
         unit_ref_unset(&u->slice);
-
-        while (u->refs)
-                unit_ref_unset(u->refs);
+        while (u->refs_by_target)
+                unit_ref_unset(u->refs_by_target);
 
         free(u);
 }
@@ -737,8 +736,8 @@ int unit_merge(Unit *u, Unit *other) {
                 return r;
 
         /* Redirect all references */
-        while (other->refs)
-                unit_ref_set(other->refs, u);
+        while (other->refs_by_target)
+                unit_ref_set(other->refs_by_target, other->refs_by_target->source, u);
 
         /* Merge dependencies */
         for (d = 0; d < _UNIT_DEPENDENCY_MAX; d++)
@@ -2493,7 +2492,7 @@ int unit_add_default_slice(Unit *u, CGroupContext *c) {
         if (r < 0)
                 return r;
 
-        unit_ref_set(&u->slice, slice);
+        unit_ref_set(&u->slice, u, slice);
         return 0;
 }
 
@@ -3130,30 +3129,32 @@ int unit_get_unit_file_preset(Unit *u) {
         return u->unit_file_preset;
 }
 
-Unit* unit_ref_set(UnitRef *ref, Unit *u) {
+Unit* unit_ref_set(UnitRef *ref, Unit *source, Unit *target) {
         assert(ref);
-        assert(u);
+        assert(source);
+        assert(target);
 
-        if (ref->unit)
+        if (ref->target)
                 unit_ref_unset(ref);
 
-        ref->unit = u;
-        LIST_PREPEND(refs, u->refs, ref);
-        return u;
+        ref->source = source;
+        ref->target = target;
+        LIST_PREPEND(refs_by_target, target->refs_by_target, ref);
+        return target;
 }
 
 void unit_ref_unset(UnitRef *ref) {
         assert(ref);
 
-        if (!ref->unit)
+        if (!ref->target)
                 return;
 
         /* We are about to drop a reference to the unit, make sure the garbage collection has a look at it as it might
          * be unreferenced now. */
-        unit_add_to_gc_queue(ref->unit);
+        unit_add_to_gc_queue(ref->target);
 
-        LIST_REMOVE(refs, ref->unit->refs, ref);
-        ref->unit = NULL;
+        LIST_REMOVE(refs_by_target, ref->target->refs_by_target, ref);
+        ref->source = ref->target = NULL;
 }
 
 int unit_patch_contexts(Unit *u) {
diff --git a/src/core/unit.h b/src/core/unit.h
index 3f411a1793..a6e21d60ce 100644
--- a/src/core/unit.h
+++ b/src/core/unit.h
@@ -84,8 +84,8 @@ struct UnitRef {
          * that we can merge two units if necessary and correct all
          * references to them */
 
-        Unit* unit;
-        LIST_FIELDS(UnitRef, refs);
+        Unit *source, *target;
+        LIST_FIELDS(UnitRef, refs_by_target);
 };
 
 struct Unit {
@@ -125,7 +125,7 @@ struct Unit {
         char *job_timeout_reboot_arg;
 
         /* References to this */
-        LIST_HEAD(UnitRef, refs);
+        LIST_HEAD(UnitRef, refs_by_target);
 
         /* Conditions to check */
         LIST_HEAD(Condition, conditions);
@@ -591,11 +591,11 @@ void unit_trigger_notify(Unit *u);
 UnitFileState unit_get_unit_file_state(Unit *u);
 int unit_get_unit_file_preset(Unit *u);
 
-Unit* unit_ref_set(UnitRef *ref, Unit *u);
+Unit* unit_ref_set(UnitRef *ref, Unit *source, Unit *target);
 void unit_ref_unset(UnitRef *ref);
 
-#define UNIT_DEREF(ref) ((ref).unit)
-#define UNIT_ISSET(ref) (!!(ref).unit)
+#define UNIT_DEREF(ref) ((ref).target)
+#define UNIT_ISSET(ref) (!!(ref).target)
 
 int unit_patch_contexts(Unit *u);